I need to know the souce of this doujin quick before my blood pressure goes up too high....ss.d..d...too late

[Gigameka] Oshioki is the source. That page is near the end of the story.

It's futa', though. So if you're not into it, don't seek it out.

I believe Desudesu did a translation for it recently.

http://g.e-hentai.org/g/253877/cdf9de2c80/ - translated doujin

baka-mazoku said:

http://g.e-hentai.org/g/253877/cdf9de2c80/ - translated doujin

Awesome. Especially love how Kanako, after being on the receiving end, went on the giving end.
Also, that's the second H-doujin where I've seen Sanae say about Kanako and Suwako, "Even though they fight all the time, they're actually very close to eah other." Is that a canon line or something?